<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>type操作符</title>
</head>
<body>
 <p>type操作符返回变量或表达式的类型。</p>
<p id="demo"></p>
 <script>
    document.getElementById("demo").innerHTML=
        typeof"john"+"<br>"+
        typeof 3.14+"<br>"
 </script>
</body>
</html>